The present invention relates to a method of locating an underground utility line and an underground utility line which has been installed in accordance with the teachings of the method.
U.S. Pat. No. 6,282,477 (Gudat et al 2001) describes the simultaneous display of an earthworking machine and an underground object as taken from a utility company map in a data format of the location of their buried utility. The patent reference describes an inherent xe2x80x9cregion of uncertaintyxe2x80x9d caused by a number of factors. One of those factors is the fact that subsurface movement can cause utility lines to move underground from their original position.
U.S. Pat. No. 6,119,376 (Stump 2000) describes an excavator navigation system for monitoring an excavator as it progresses along an excavation route and detecting any deviations from the predetermined excavation route. To increase the accuracy of the system, a mobile transponder on the excavator is supplemented by one or more base transponders selectively positioned along the excavation route.
What is required is a method of locating an underground utility line which will reduce or eliminate the xe2x80x9cregion of uncertaintyxe2x80x9d.
According to a first aspect of the present invention there is provided a method of locating an underground utility line. A first step involves securing transponders along a length of an underground utility line at regular spaced intervals. A second step involves interrogating the transponders to receive transponder signals. A third step involves ascertaining the position of the transponder signals and extrapolating positioning of the underground utility line from the transponder signals.
With the method, as described above, signals from the transponders can be used to obtain an accurate indication of the positioning of the underground utility.
Although beneficial results may be obtained through the use of the method, as described above, even more beneficial results may be obtained when the transponder signals include vital information regarding the utility line. The transponder signals can communicate whether the utility line is a water line, a natural gas line, an electrical cable or a fiberoptic cable. It can also contain detailed information about the utility line. For example, for a gas line there can be indicated the size of the line, the pressure that the gas is under and an emergency contact number.
There are various ways in which the location of transponders emitting radio frequency signals can be determined. Beneficial results have been obtained when global positioning system (GPS) co-ordinates are determined for each of the transponder signals and the transponder signals from the transponders are displayed on a grid of GPS co-ordinates.
According to a second aspect of the present invention there is provided, in combination, an underground utility line having transponders secured along it""s length at regular spaced intervals and a display displaying on a grid of GPS co-ordinates, GPS co-ordinates of transponder signals from each of the transponders, along with positioning of the underground utility line as extrapolated from the transponder signals.